Universal Serial Bus (“USB”) and External Serial Advanced Technology Attachment (“eSATA”) are two types of commonly used standards for connectors. Each of these standards have undergone rapid development since their inception.
The USB standard that governs the design of the USB connections has undergone several revisions since its earliest release in 1994. The first widely adopted version, USB 1.1, specified data rates of 1.5 Mbit/s (“Low-Bandwidth”) and 12 Mbit/s (“Full-Bandwidth”). USB 1.1 was replaced by USB 2.0 in 2000. USB 2.0 provided a higher maximum data transfer rate of 480 Mbit/s (“Hi-Speed”). In this version, the USB 2.0 cable has four wires: two wires for power (+5 volts and ground) and a twisted pair of wires for carrying data. In the USB 2.0 design, as well as USB 1.1, data is transmitted in one direction at a time (downstream or upstream).
In 2008, a new USB 3.0 standard was announced. USB 3.0 includes a new “SuperSpeed” bus, which provides a fourth data transfer rate of 5.0 Gbit/s. In order to achieve this increased throughput, the USB 3.0 cable has a total of eight wires: two wires for power (+5 volts and ground), the twisted pair for carrying non-SuperSpeed data (allows backward compatibility with earlier versions of USB devices), and two differential pairs for carrying SuperSpeed data. Full-duplex signaling occurs over the two differential pairs. To date, adoption of the USB 3.0 standard has been slow due to the need to re-design motherboard hardware that supports the USB 3.0 standard, and the need to revise operating systems to support the USB 3.0 standard.
Traditionally, SATA is an internal computer bus interface for connecting host bus adapters to mass storage devices. First generation SATA interfaces (“SATA I”) specified data transfer rates 1.5 Gbit/s. Second generation SATA interfaces (“SATA II”) specified data rates of 3.0 Gbit/s. All SATA data cables meeting the SATA spec are rated for 3.0 Gbit/s. In 2009, the third generation SATA interface (“SATA III”) was released, specifying a peak throughput of 6 Gbit/s. The SATA III standard is backwards compatible with SATA II. eSATA was standardized in 2004 and provides a variant of the SATA protocols for external connectively. In each version of eSATA (“eSATA I”, “eSATA II”, and “eSATA III”), the hardwire includes two differential pairs of wires, plus an additional three ground wires. Because eSATA uses the same ATA protocol as a computer's internal hard drive, a bridge chip is not needed to translate from the computer's internal ATA protocol to another protocol, such as USB. However, while most computers use SATA standards internally, many computers do not include external SATA connectors, opting instead to include external USB connectors.
Because eSATA connectors are not yet widely available, it is desirable to provide eSATA connectors that include full backward and forward compatibility between the SATA I, II, and III standards, in combination with USB connectors that include full backward and forward compatibility between the USB 2.0 and 3.0 standards.